JP6987554B2 - Non-destructive inspection equipment and its method - Google Patents

Description

The present invention relates to a non-destructive inspection device and a method thereof for non-destructively detecting defects, density unevenness, other abnormalities, etc. inside an object using ultrasonic waves.

Conventionally, ultrasonic flaw detection inspection, which uses ultrasonic waves to perform non-destructive inspection, is known. In ultrasonic flaw detection inspection, ultrasonic pulse signals are propagated to the surface or inside of a metal material, etc., and the reflected signal from acoustically discontinuous parts, reflection intensity, propagation time, etc., cause scratches inside the material. It is a technology that evaluates length, shape, etc. non-destructively and judges the quality of the product according to inspection standards. Ultrasonic waves propagate inside an object and are reflected by defects such as cracks. The pulse reflection method, which identifies the presence or absence of defects and the position by receiving this reflected wave (echo), is mainly used in ultrasonic flaw detection inspection.

Ultrasonic reflection occurs at the interface where the "acoustic impedance" differs greatly. The acoustic impedance is a physical characteristic value defined by "density ρ of an object" x "sound velocity c in an object". For example, the acoustic impedance of iron is 46.4 × 10 ⁶ Nsm ^-3 and the acoustic impedance of dry air is 428.6 Nsm ^-3 . In the conventional ultrasonic echo, since the inspection method uses the reflection of sound waves at the interface with defects, it is difficult to detect defects such as density unevenness in which the acoustic impedance changes only slightly. ..

In order to detect minute defects by ultrasonic waves, the waveform of the transmitted wave with respect to the incident wave is frequency-analyzed to obtain the fundamental wave and harmonics, and the presence or absence of minute defects is determined from the ratio of the amplitude of the fundamental wave to the amplitude of the harmonics. Is known and is described in Patent Document 1.

In addition, cracks that are not clear by conventional methods are difficult to detect by ordinary methods because ultrasonic waves pass through them. Therefore, when an ultrasonic signal of a continuous pulse is projected onto the object to be inspected and passed through a crack, a harmonic component and a fractional wave component are observed in addition to the fundamental frequency component of the ultrasonic wave depending on the conditions. This observation attempts to detect cracks that are difficult to detect by ordinary methods.

Furthermore, a special device is required to generate continuous pulse ultrasonic waves. In addition, continuous pulse ultrasonic waves interfere with waves when many reflected waves are generated, such as in a multilayer member, and correct analysis cannot be performed. Therefore, the single ultrasonic pulse that has entered the inside of the object to be inspected is received by the receiving unit, and the instantaneous frequency of the decay waveform of the received single ultrasonic pulse and its time change (change over time) are obtained. Then, Patent Document 2 discloses an abnormal situation that cannot be found by a conventional method using a single ultrasonic pulse signal, is less susceptible to interference of reflected waves, and captures a small amount of frequency change. Has been described.

Japanese Unexamined Patent Publication No. 2004-340807 Japanese Patent No. 5105384

In the method described in Patent Document 2 which is the above-mentioned prior art, the decay waveform of the received single ultrasonic pulse signal is approximated by an approximate expression represented by the envelope and the phase of the decay waveform, and the phase in the approximate expression is approximated. Obtain the instantaneous angular frequency from. Then, it is necessary to diagnose the state of the object to be inspected based on the time change of the instantaneous angular frequency, and the procedure is complicated. In addition, it has been difficult to detect defects such as density unevenness in which the acoustic impedance changes only slightly.

An object of the present invention is to solve the above-mentioned problems of the prior art and to obtain a non-destructive inspection method and apparatus for detecting defects (for example, density unevenness) in which the acoustic impedance changes only slightly with a simple configuration.

In order to achieve the above object, the non-destructive inspection apparatus of the present invention propagates ultrasonic waves to an object to be inspected by an ultrasonic transmitter, receives the ultrasonic waves by an ultrasonic receiver, and receives the ultrasonic waves by a change in propagation time. In a non-destructive inspection device that detects defects in an inspection object, an ultrasonic transmitter 1 that transmits ultrasonic waves of a first frequency and ultrasonic waves that transmit ultrasonic waves of a second frequency different from the first frequency. The transmitter 2 is provided with the ultrasonic transmitter 1 and the ultrasonic receiver for receiving the ultrasonic waves transmitted from the ultrasonic transmitter 1, based on the humming waveform received by the ultrasonic receiver. It is for determining the presence or absence of defects in the inspected object.

As a result, the ultrasonic waves received by the ultrasonic receiver become beat waveforms, and even with a slight delay in propagation time, the phase of the beat waveform changes significantly, resulting in large changes in acoustic impedance such as uneven density of the inspected object. Even defects that do not exist can be detected.

Further, in the above, the ultrasonic transmitter 1 and the ultrasonic transmitter 2 are arranged on one side of the object to be inspected, and the ultrasonic receiver is arranged on the other surface of the object to be inspected. It is desirable that the ultrasonic waves pass through the inside of the object to be inspected and propagate to the ultrasonic receiver.

Further, in the above, the ultrasonic transmitter 1, the ultrasonic transmitter 2, and the ultrasonic receiver are arranged on one side of the object to be inspected, and the ultrasonic wave is reflected inside the object to be inspected. It is desirable that the sound is propagated to the ultrasonic receiver.

Further, in the above, it is desirable that the first frequency differs from the second frequency by 0.3 to 3%.

Further, in the above, the frequency of either the ultrasonic transmitter 1 or the ultrasonic transmitter 2 is set to 290 to 310 kHz, and the other frequency has a frequency difference of 1 to 10 kHz with respect to the one frequency. It is desirable to do.

Further, in the above, it is desirable that the number of ridges of the envelope of the beat waveform is 1 to 3 inside the object to be inspected.

Further, in the above, it is desirable that the ultrasonic wave produced by the ultrasonic transmitter 1 or the ultrasonic transmitter 2 is an ultrasonic burst wave having a finite transmission duration.

Further, in the non-destructive inspection method of the present invention, an ultrasonic wave is propagated to an inspected object by an ultrasonic transmitter, the ultrasonic wave is received by an ultrasonic receiver, and a defect of the inspected object is detected by a change in propagation time. This is a non-destructive inspection method for detecting, in which ultrasonic waves having a first frequency are transmitted from the ultrasonic transmitter 1 and ultrasonic waves having a second frequency different from the first frequency are transmitted from the ultrasonic transmitter 2 from the ultrasonic transmitter 2. The ultrasonic waves transmitted from the ultrasonic transmitter 1 and the ultrasonic transmitter 2 propagating inside the object to be inspected are received as a growl waveform by the ultrasonic receiver and received by the ultrasonic receiver. It is characterized in that the presence or absence of a defect in the object to be inspected is determined based on the swelling waveform.

Further, in the above, the ultrasonic transmitter 1 and the ultrasonic transmitter 2 are arranged on one side of the object to be inspected, and the ultrasonic receiver is arranged so as to face the other surface of the object to be inspected. Is desirable to pass through the inside of the object to be inspected and propagate to the ultrasonic receiver.

Further, in the above, the ultrasonic transmitter 1, the ultrasonic transmitter 2, and the ultrasonic receiver are arranged on one side of the object to be inspected, and the ultrasonic waves are reflected inside the object to be inspected. It is desirable to propagate to the ultrasonic receiver.

According to the present invention, the ultrasonic wave received by the ultrasonic receiver becomes a beat waveform, and the phase of the beat waveform changes greatly even with a slight delay in propagation time. Therefore, the test is performed with a relatively simple configuration. It is possible to detect defects such as uneven density of objects that do not significantly change the acoustic impedance.

Basic configuration diagram of the non-destructive inspection device according to the embodiment according to the present invention. A graph of time vs. amplitude showing the waveform received by the ultrasonic receiver in one embodiment. Basic configuration diagram of conventional non-destructive inspection equipment Configuration diagram showing the case where there is a defect that is difficult to detect in the past Basic configuration diagram of non-destructive inspection device according to other embodiments Figure showing the composition of the experiment in the atmosphere Graph showing the results of experiments in the atmosphere

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The pulse reflection method and the transmission method are known as ultrasonic flaw detection inspections. The pulse reflection method propagates an ultrasonic pulse signal to the surface or inside of a metal material, etc., and causes scratches or length inside the material due to the reflected signal from acoustically discontinuous parts, reflection intensity, propagation time, etc. The shape and the like are judged as good or bad. Then, ultrasonic waves (longitudinal waves whose vibration direction is the same as the traveling direction of the waves) are propagated vertically from the ultrasonic transmitter to the object to be inspected, and a part of them is reflected by internal defects and transmitted. Defects are detected by returning to the vessel.

In the transmission type, an ultrasonic transmitter is placed on one side of the object to be inspected and an ultrasonic receiver is placed on the other side to receive the ultrasonic waves propagated inside the object to be inspected. The existence of defects is known from the change in propagation time.

An ultrasonic element is used for transmitting and receiving ultrasonic waves. The ultrasonic element is an element that generates ultrasonic waves by applying electric energy or converts ultrasonic vibration energy into an electric signal. A barium titanate vibrating element that utilizes the piezoelectric phenomenon is used. The piezoelectric element vibrates when an AC voltage is applied, has a unique frequency, and vibrates efficiently by applying an AC voltage of the same frequency as that frequency.

FIG. 1 is a basic configuration diagram of a non-destructive inspection device according to an embodiment of the present invention. FIG. 2 is a time-to-amplitude graph showing a waveform received by the ultrasonic receiver 3, FIG. 3 is a basic configuration diagram of a conventional non-destructive inspection device, and FIG. 4 shows a case where there is a defect that is difficult to detect in the past. It is a block diagram. In the configuration shown in FIG. 1, the ultrasonic transmitters 1 and 2 are arranged on one side of the object 4 to be inspected, and the ultrasonic receiver 3 is arranged on the other side. Therefore, it corresponds to a transmission type ultrasonic flaw detection inspection.

The object 4 to be inspected moves in the direction of the arrow 5, and the ultrasonic transmitters 1 and 2 and the ultrasonic receiver 3 are fixed. Alternatively, conversely, the object 4 to be inspected is fixed, and the ultrasonic transmitters 1 and 2 and the ultrasonic receiver 3 are moved. The ultrasonic transmitters 1 and 2 simultaneously generate ultrasonic waves having different frequencies. That is, the ultrasonic transmitter 1 generates the first frequency, the ultrasonic transmitter 2 generates the second frequency, and the propagating ultrasonic waves 1 and 2 from the ultrasonic transmitters 1 and 2 are received by the ultrasonic receiver 3. By doing so, the defect is detected by the change in the propagation time transmitted by the defect of the object 4 to be inspected. The ultrasonic transmitters 1 and 2 and the ultrasonic receiver 3 may be arranged so as to sandwich the object to be inspected 4.

In the ultrasonic transmitters 1 and 2, ultrasonic waves of different frequencies propagate inside the object 4 as the propagating ultrasonic waves 1 and 2, so that the ultrasonic receiver 3 is a wave in which two ultrasonic waves overlap. , Receives a growl waveform. Propagation ultrasonic waves 1 and 2 follow different paths to reach the ultrasonic receiver 3.

On the other hand, in the case of the conventional non-destructive inspection device, in the case of the transmission type, the ultrasonic transmitter 1 is arranged on one side of the object 4 to be inspected and the ultrasonic receiver 3 is arranged on the other side as shown in FIG. In No. 7, the defect was detected by blocking the ultrasonic wave. Further, in the reflection type, only the ultrasonic transmitter 1 is arranged on one side of the object 4 to be inspected, the ultrasonic transmitter 1 has the function of the ultrasonic receiver, and the ultrasonic transmitter 1 receives the reflected wave. There is. Then, the defect was detected by the ultrasonic wave being quickly reflected by the defect 7 and returning to the ultrasonic transmitter 1.

In the case of defects such as clear cracks as shown in FIG. 3, the defect 7 can be detected even with a conventional non-destructive inspection device, but there is a large change in acoustic impedance such as density unevenness due to the altered part as shown in FIG. In the case of the defect 8, the ultrasonic wave is not blocked or reflected. Therefore, as shown in FIG. 4, the difference in propagation time from the ultrasonic transmitter 1 to the ultrasonic receiver 3 between the ultrasonic wave propagating in the portion with the defect 8 and the ultrasonic wave propagating in the portion without the defect 8. Was very small, and it was extremely difficult to detect defects in which the acoustic impedance did not change significantly.

On the other hand, in the embodiment shown in FIG. 1, the distance from the ultrasonic transmitter 1 to the ultrasonic receiver 3 and the distance from the ultrasonic transmitter 2 to the ultrasonic receiver 3 are substantially the same. If the object 4 to be inspected is a completely homogeneous and homogeneous object, there is no difference in the speed of sound between the two paths of the propagating ultrasonic waves 1 and 2. Therefore, the propagating ultrasonic waves 1 and 2 reach the ultrasonic wave receiver 3 at the same time.

If a defect exists in one of the paths until the propagating ultrasonic waves 1 and 2 reach the ultrasonic receiver 3, the sound velocity of the propagating ultrasonic waves 1 and 2 changes by passing through the defect. Therefore, the propagation time until the propagating ultrasonic waves 1 and 2 reach the ultrasonic receiver 3 is slightly different from that when the inspected object 4 is a completely homogeneous and homogeneous object.

Since the ultrasonic waves received by the ultrasonic receiver 3 are propagating ultrasonic waves 1 and 2 having different frequencies, they are in an overlapping state and a beat waveform. Since the envelope of the beat waveform changes greatly due to the phase change of the two propagating ultrasonic waves 1 and 2, it is possible to detect even a slight difference in the propagating time by the propagating ultrasonic waves 1 and 2. .. It is desirable that the ultrasonic wave transmission time be an ultrasonic burst wave having a finite transmission duration in order to accurately detect the difference in propagation time.

Further, the thickness of the object 4 to be inspected, that is, the distance from the ultrasonic transmitters 1 and 2 to the ultrasonic receiver 3, is from at least 1 of the envelope of the beat waveform in the time it takes for the ultrasonic wave to reach the ultrasonic receiver 3. Make it about 3 cycles. This makes it possible to prevent erroneous detection due to the ultrasonic transmission time being too long.

FIG. 2 shows a beat waveform generated by the ultrasonic receiver 3 by transmitting different frequencies between the ultrasonic transmitter 1 and the ultrasonic transmitter 2. The frequency in the figure below is 1.1 times the frequency in the figure above. The beat waveform is a superposition of two propagating ultrasonic waves 1 and 2, and the shape and the envelope shown by the dotted line are greatly affected by the phase of each propagating ultrasonic wave, that is, the propagation time.

The above figure shows the case where there is no difference between the propagation time from the ultrasonic transmitter 1 to the ultrasonic receiver 3 and the propagation time from the ultrasonic transmitter 2 to the ultrasonic receiver 3, and there is no defect. Is. The figure below shows the received waveform when the propagating ultrasonic wave 2 by the ultrasonic transmitter 2 arrives at the ultrasonic receiver 3 with a delay of 4/6 cycle. As shown in FIG. 2, the phase of the beat waveform changes significantly even with a slight delay in propagation time.

として表現できる。このときｃｏｓの項はうなり波形のエンベロープを示し、ｓｉｎの項はエンベロープ内部の波形を示している。 The details of the beat waveform and the change in phase will be described. Let the propagating ultrasonic waves 1 and 2 be F ₁ and F ₂ . Assuming that the respective frequencies f ₁ and f ₂ , the respective angular frequencies ω ₁ and ω ₂ , and the initial phases are φ ₁ and φ ₂ , then f _{1 = 2π ω 1} and f _{2 = 2} π ω 2, so that the propagating ultrasonic waves Assuming that 1 and 2 are 1, F ₁ = sin (2πω ₁ t + φ ₁ ) and F ₂ = sin (2πω ₂ t + φ ₂ ). The beat waveform F generated by superimposing _{F 1} and F _{2 is}

Can be expressed as. At this time, the cos term indicates the envelope of the beat waveform, and the sin term indicates the waveform inside the envelope.

Here the propagation propagation time F ₂ slightly delayed an ultrasonic 2, the delay time between Delta] t. However, the delay time Δt is if within the period of _{F 2 (1 / f 2)} , F 2 can be expressed as Equation 2 using the time t.

式３において、ｃｏｓの項はうなり波形のエンベロープを示し、ｓｉｎの項はエンベロープ内部の波形を示している。したがって、伝播超音波２であるＦ_２の遅れがうなり波形Ｆのエンベロープの位相に影響を与えていることが分かる。 Then, the generated beat waveform F is given by Equation 3.

In Equation 3, the cos term indicates the envelope of the beat waveform, and the sin term indicates the waveform inside the envelope. Therefore, it can be seen that influence the envelope of the phase propagation ultrasonic 2. The term F ₂ of delay beat waveform F.

_{In order to clarify the degree of influence of the frequencies f 1} and f ₂ of the propagating ultrasonic waves 1 and 2, the equation 3 is modified into the equation 4.

Since the cos term also indicates the envelope of the beat waveform in Equation 4, when _{the propagation time of F 2} which is the propagating ultrasonic wave 2 is delayed by Δt, the envelope of the beat waveform F becomes.
It can be seen that the shape is out of phase by (ω ₂ / ω ₁ − _{ω 2) Δt.} If the frequency f _{1 of the propagating ultrasonic wave 1 = 301 kHz and the frequency f 2} of the propagating ultrasonic wave 2 = 300 kHz, the deviation of the beat waveform will be.
(Ω ₂ / ω ₁ −ω ₂ ) Δt = (f ₂ / f ₁ −f _{2 ) Δt = 300Δt, and if the propagation time of F 2} , which is the propagating ultrasonic wave 2, is delayed by Δt, the detection is magnified 300 times. I know I can do it. Here, _{it is desirable that the amount of deviation between f 1} and f ₂ is 0.3 to 3% with respect to either frequency from the viewpoint of beat waveform generation and detection sensitivity.

FIG. 5 is a basic configuration diagram of a non-destructive inspection device according to another embodiment. The object 4 to be inspected moves in the direction of the arrow 5, and the ultrasonic transmitters 1 and 2 and the ultrasonic receiver 3 are fixed to one side (upper side) of the object 4 to be inspected. Alternatively, conversely, the object 4 to be inspected is fixed, and the ultrasonic transmitters 1 and 2 and the ultrasonic receiver 3 are moved. The ultrasonic transmitters 1 and 2 simultaneously generate ultrasonic waves of different frequencies. The propagating ultrasonic waves 1 and 2 from the ultrasonic transmitters 1 and 2 receive the reflected wave from the other surface (lower side) of the object 4 to be inspected by the ultrasonic receiver 3.

If there is a defect inside the object 4 to be inspected, a part of the propagating ultrasonic waves 1 and 2 is reflected by the internal defect and returns to the ultrasonic transmitter. Then, the defect is detected by the change in the propagation time transmitted by the defect. It is a so-called reflection type, and as described with reference to FIG. 1, the ultrasonic transmitters 1 and 2 are ultrasonic waves because ultrasonic waves having different frequencies propagate inside the inspected object 4 as propagating ultrasonic waves 1 and 2. The receiver 3 receives a wave in which two ultrasonic waves overlap, that is, a humming waveform.

The distance from the ultrasonic transmitter 1 to the ultrasonic receiver 3 and the distance from the ultrasonic transmitter 2 to the ultrasonic receiver 3 are substantially the same. If the object 4 to be inspected is a completely homogeneous and homogeneous object, there is no difference in the speed of sound between the two paths of the propagating ultrasonic waves 1 and 2. Therefore, the propagating ultrasonic waves 1 and 2 reach the ultrasonic wave receiver 3 at the same time.

If a defect exists in one of the paths until the propagating ultrasonic waves 1 and 2 reach the ultrasonic receiver 3, the sound velocity of the propagating ultrasonic waves 1 and 2 changes by passing through the defect. Therefore, the propagation time until the propagating ultrasonic waves 1 and 2 reach the ultrasonic receiver 3 is slightly different from that when the inspected object 4 is a completely homogeneous and homogeneous object.

Since the ultrasonic waves received by the ultrasonic receiver 3 are propagating ultrasonic waves 1 and 2 having different frequencies, they are in an overlapping state and a beat waveform. Since the envelope of the beat waveform changes greatly due to the phase change of the two propagating ultrasonic waves 1 and 2, it is possible to detect even a slight difference in the propagating time by the propagating ultrasonic waves 1 and 2. ..

According to the beat waveform, as an example in which ultrasonic waves can be detected even if the propagation time is short, an example actually performed in the atmosphere will be described. FIG. 6 is a diagram showing the configuration of an experiment in the atmosphere, in which ultrasonic waves having different frequencies are transmitted from the ultrasonic transmitters 1 and 2 and received as a beat waveform by the ultrasonic receiver 3. The ultrasonic transmitters 1 and 2 and the ultrasonic receiver 3 are placed in the atmosphere, and the frequency of the ultrasonic transmitter 1 is 300 kHz, the frequency of the ultrasonic transmitter 2 is 293 kHz, and the frequency difference is 7 kHz. Alternatively, the frequency of the ultrasonic transmitter 1 may be 293 kHz, and the frequency of the ultrasonic transmitter 2 may be 300 kHz.

The distance between the ultrasonic transmitters 1 and 2 and the ultrasonic receiver 3 is 450 mm, and the transmission pulse time width is 0.35 ms. Therefore, the envelope of the beat waveform is generated by about 2.5 peaks. The frequency of either the ultrasonic transmitter 1 or the ultrasonic transmitter 2 is set to around 300 kHz, for example, 290 to 310 kHz, and the other frequency has a frequency difference of 1 to 10 kHz with respect to one frequency. It is practical to set the number of ridges of the envelope to about 1 to 3 ridges.

FIG. 7 is a graph showing the results of experiments in the atmosphere, and is the result of measuring the received waveform with reference to the transmission pulse start time of ultrasonic waves. The upper and lower figures are obtained by changing the measurement time. The horizontal axis is time, and the vertical axis is the amplitude (V) of the signal received by the ultrasonic receiver 3. In addition, since the experiment was conducted in the atmosphere, the density of the atmosphere changed slightly depending on the measurement time. This is an experiment to confirm whether this change is measurable. In FIG. 7, the time when the transmission pulse is received is shown by the reference line a. In the upper and lower figures, the propagation time differs due to the change in the density of the atmosphere, so that the reception time should be different and the reception waveform at the reference line a should be different. However, the difference cannot be seen from the figure, and further measurement is extremely difficult.

On the other hand, looking at the envelope of the beat waveform, the position of the apex of the beat is the reference line b in the upper figure and the reference line c in the lower figure. That is, the envelope of the beat waveform changes greatly according to the change in the density of the atmosphere depending on the measurement time. In this case, it can be confirmed that the difference between the reference line b and the reference line c, which is the change width, is 0.03 ms. As shown in FIG. 7, the beat waveform changes greatly even with a slight delay in propagation time, and by detecting the arrival time of the apex of the beat waveform, the acoustic impedance changes only slightly (density unevenness, etc.). Can be detected with high sensitivity.

Although a low-frequency ultrasonic element can transmit ultrasonic waves with low energy, its beam diameter is large and it is not suitable for detecting small defects when driven at about 40 kHz. Furthermore, high-frequency elements with a small beam diameter require higher energy to drive, and it is difficult to synthesize high-frequency signals of about 300 kHz in an electric circuit and drive them with high output without distortion. there were.

Therefore, in order to transmit ultrasonic waves, the ultrasonic transmitters 1 and 2 use a high-voltage on / off signal, that is, a switch circuit that drives the ultrasonic element in a pulsed manner with a rectangular wave, as an ultrasonic burst wave that is continuous for a predetermined time. It is desirable to send.

Then, the signal obtained by the ultrasonic receiver 3 is sampled by the analysis device, A / D converted, and recorded in the memory. Furthermore, it is good to determine the presence or absence of defects from the received beat waveform based on the difference in propagation time.

If the ultrasonic transmitter 1 and the ultrasonic transmitter 2 generate a pulse signal which is a square wave and transmit the frequency in the vicinity of 300 kHz, the beam size can be reduced and the defect detection sensitivity can be improved. Also, if the switch circuit is driven in a pulsed manner with a square wave, it does not amplify the analog signal that causes amplitude distortion, so the drive circuit itself is compared to the conventional one with a frequency of about 40 kHz. Does not require unnecessary power consumption.

Further, since the ultrasonic receiver 3 produces a beat waveform by transmitting the ultrasonic transmitters 1 and 2 at different frequencies, the beat waveform electrically synthesized by one ultrasonic transmitter 1 can be obtained. It does not amplify the analog signal as compared to the case of transmission.

Furthermore, the configuration for generating ultrasonic waves is simplified, and wasteful power consumption is not required. Then, it is possible to suppress the cost and achieve higher accuracy with energy saving. Further, the signal received by the ultrasonic receiver 3 may be analyzed after removing noise outside the band, amplifying the signal, and the like.

1 ultrasonic transmitter 1
2 ultrasonic transmitter 2
3 Ultrasonic receiver 4 Inspected object 5 Arrow 6 Beat waveform 7 Defects (defects such as cracks)
8 Defects (defects such as uneven density)
a, b, c reference line

Claims (10)

In a non-destructive inspection device that propagates ultrasonic waves to an inspected object by an ultrasonic transmitter, receives the ultrasonic waves by an ultrasonic receiver, and detects defects in the inspected object by a change in propagation time.
An ultrasonic transmitter 1 that transmits ultrasonic waves of the first frequency,
An ultrasonic transmitter 2 that transmits an ultrasonic wave having a second frequency different from the first frequency,
The ultrasonic receiver 1 for receiving the propagating ultrasonic waves from the ultrasonic transmitter 1 and the ultrasonic transmitter 2 and the ultrasonic receiver.
Equipped with
The ultrasonic transmitter 1 and the ultrasonic transmitter 2 simultaneously generate the ultrasonic waves, and the ultrasonic receiver receives a beat waveform in which the propagating ultrasonic waves having different frequencies are overlapped with each other, and the beat waveform is received. A non-destructive inspection apparatus for determining the presence or absence of defects in the inspected object based on the above. The ultrasonic transmitter 1 and the ultrasonic transmitter 2 are arranged on one side of the object to be inspected, the ultrasonic receiver is arranged facing the other surface of the object to be inspected, and the ultrasonic wave is the object to be inspected. The non-destructive inspection apparatus according to claim 1, wherein the ultrasonic wave receiver is transmitted through the inside of the ultrasonic wave receiver. The ultrasonic transmitter 1, the ultrasonic transmitter 2, and the ultrasonic receiver are arranged on one side of the object to be inspected, and the ultrasonic waves are reflected inside the object to be inspected to the ultrasonic receiver. The non-destructive inspection apparatus according to claim 1, wherein the non-destructive inspection device is characterized by being propagated. The nondestructive inspection apparatus according to any one of claims 1 to 3, wherein the first frequency differs from the second frequency by 0.3 to 3%. A claim characterized in that the frequency of either the ultrasonic transmitter 1 or the ultrasonic transmitter 2 is 290 to 310 kHz, and the frequency of the other is a frequency difference of 1 to 10 kHz with respect to the one frequency. Item 4. The non-destructive inspection apparatus according to any one of Items 1 to 4. The non-destructive inspection apparatus according to any one of claims 1 to 5, wherein the number of peaks of the envelope of the beat waveform is 1 to 3 inside the object to be inspected. The method according to any one of claims 1 to 6, wherein the ultrasonic wave produced by the ultrasonic transmitter 1 or the ultrasonic transmitter 2 is an ultrasonic burst wave having a finite transmission duration. Non-destructive inspection equipment. A non-destructive inspection method in which an ultrasonic wave is propagated to an inspected object by an ultrasonic transmitter, the ultrasonic wave is received by an ultrasonic receiver, and a defect in the inspected object is detected by a change in propagation time.
An ultrasonic transmitter 1 that transmits ultrasonic waves of the first frequency,
An ultrasonic transmitter 2 that transmits an ultrasonic wave having a second frequency different from the first frequency,
The ultrasonic receiver 1 and the ultrasonic receiver for receiving the propagating ultrasonic waves from the ultrasonic transmitter 2 are provided .
The ultrasonic transmitter 1 and the ultrasonic transmitter 2 simultaneously generate the ultrasonic waves, and the ultrasonic receiver receives a beat waveform in which the propagating ultrasonic waves having different frequencies are overlapped with each other, and the beat waveform is received. A non-destructive inspection method comprising determining the presence or absence of defects in the object to be inspected based on the above. The ultrasonic transmitter 1 and the ultrasonic transmitter 2 are arranged on one side of the object to be inspected, and the ultrasonic receiver is arranged facing the other surface of the object to be inspected, and the ultrasonic wave is the object to be inspected. The non-destructive inspection method according to claim 8, wherein the ultrasonic wave is transmitted through the inside of the ultrasonic wave receiver. The ultrasonic transmitter 1, the ultrasonic transmitter 2, and the ultrasonic receiver are arranged on one side of the object to be inspected, and the ultrasonic waves are reflected inside the object to be inspected and sent to the ultrasonic receiver. The non-destructive inspection method according to claim 8, wherein the transmission is performed.

Images